The present invention relates to a system for the artificial triggering of lightning flashes. It applies to the triggering of lightning flashes to cause them to follow a preferred path in space.
There are two fundamental principles for artificially triggering lightning flashes.
According to the first principle, a small hail stopping-type rocket is launched into a storm cloud and trails behind it a thin wire made from a conductive material and electrically connected to the ground. This leads to a lightning flash, whose ground impact point is fixed beforehand.
According to the second principle, instead of guiding the lightning flash to the ground by means of a metallic wire, it is given the free choice of its path over the last few hundred meters before striking the ground. This is brought about by using a mixed wire, which is firstly insulating and then conductive. This process is particularly interesting for studying impact mechanisms and for testing protective equipment, such as lightning arresters, lightning conductors, shielding, etc.
For both these principles, the lightning flash triggering success rate is closely linked with the human and technical intervention speeds.
The first is difficult to improve, whereas the second is dependent on the construction of the triggering system.
In the present state of the art, the most limiting element is the small diameter pay-out reel, which does not make it possible to unwind the wire with the same speed as that of the rocket. When using a commercial rocket, e.g. the Ruggieri 614, it is necessary to modify the same for the purpose of reducing its speed. This is very difficult, because it involves machining the black powder power plant. In addition, the metallic rocket launcher is very heavy and complicated, which also requires a damping or shock absorbing system for regularizing the unwinding of the roll of wire.
In order to unwind a mixed wire, use has hitherto been made of a pay-out reel pulled by the rocket. This system does not make it possible to unwind a mixed wire (e.g. Kevlar plus copper) at speeds exceeding 100 m/sec. The thus slowed-down rocket increases the risk of failure.
For both these procedures, an explosive is located in the rocket nose cone and on exploding at the end of the trajectory shatters the rocket into small pieces. This explosive unit which is necessary for the dispersion of the fragments, has disadvantages from the safety standpoint with respect to the storage, transportation, handling of rockets, etc.